For the cupcakes: Preheat the oven to 350 degrees F. Line a standard muffin pan with 12 cupcake liners.
Combine the red wine, flour, sugar, cocoa, baking powder, baking soda and salt in the bowl of an electric stand mixer. Whip on medium speed for 2 minutes. Scrape down the sides of the bowl, and then add the vegetable oil and sour cream.
Mix on medium speed for 1 additional minute. Scrape down the sides of the bowl, and then add the eggs and vanilla extract.
Mix on medium speed for 1 minute. Fill the cupcake liners three-quarters full with batter and bake until golden brown and baked through, about 25 minutes. Cool the cupcakes completely.
For the ganache: In a medium saucepot, bring the red wine and heavy cream to a rolling simmer.
Remove from the heat and stir in the chocolate with a whisk. Stir until the chocolate is fully melted and emulsified. Stir in the corn syrup.
Pour into a small bowl and wrap tightly. Allow to cool at room temperature for at least 2 hours, until the ganache has fully set.
Place the ganache into a pastry bag fitted with a medium round tip.
For the buttercream: In a double boiler, combine the egg whites, sugar and cabernet wine powder. Stir with a whisk until the mixture is warm and the sugar is fully dissolved.
Pour the warm egg white mixture into the bowl of an electric stand mixer. Whip on high speed until the meringue cools and stiff peaks are formed.
Mix in the softened butter.
Place into a piping bag fitted with a small round tip.
To assemble: Using an apple corer, remove the center core of the baked cupcakes and fill each with 2 cherries. Pipe cabernet-zinfandel chocolate ganache generously on top of the cupcakes, and top with cabernet buttercream, piped to look like a cluster of grapes.
